Thin-film transistors (TFTs) fabricated from unconventional materials and by unconventional methodologies are of interest for future low-cost electronic applications such as RF-ID cards, flexible displays, and sensors. Transistors are the key components used for current modulation and switching in all modern electronic devices. The basic working principle of TFTs is that the channel source and drain current (IDS) in saturation is modulated by the source-gate bias (VG) according to Eq. 1:
                              I          DS                =                              W                          2              ⁢                                                          ⁢              L                                ⁢          μ          ⁢                                          ⁢                                                    C                i                            ⁡                              (                                                      V                    G                                    -                                      V                    T                                                  )                                      2                                              (        1        )            where W/L is the channel width/length, Ci is the dielectric capacitance per unit area, μ is the charge carrier mobility, VG is the source-gate voltage, and VT is the threshold voltage. Depending on the charge carrier sign in the channel between source and drain, the semiconductor is either hole-(p-type) or electron-transporting (n-type). The two most important parameters governing TFT performance are the field-effect mobility (μ) and the current on/off ratio (Ion/Ioff). These parameters define the drift velocity of the charge carriers in the semiconductor layer under the source/drain electric field and the current modulation between the TFT “on” and “off” states upon a gate voltage change, respectively.
Over the past two decades, solution-processable organic, inorganic, and polymeric semiconductors were developed due to attractions such as printability, the possibility of large area fabrication, low-cost device fabrication, and compatibility with mechanically flexible substrates. Despite recent progress, one principal limitation of these semiconductors is their relatively low carrier mobilities, which are well below those of most silicon-based high-performance materials. As a result, TFTs fabricated from these semiconductors require high operating voltages to attain usable drain current (IDS).
For low power applications such as RF-ID tags, flat panel displays, and portable electronics, it is important to achieve high TFT drain current (IDS) at acceptably low operating voltages. Without changing device geometry (W and L) and semiconductor material (μ), an alternative to overcome these mobility limitations is to increase the gate dielectric capacitance Ci given by Eq. 2
                              C          i                =                              ɛ            0                    ⁢                      k            d                                              (        2        )            From Eq. 2, it can be seen that operating bias reduction can be achieved by either increasing the dielectric constant (k) or decreasing the thickness (d) of the gate dielectric layer. An attractive approach is to employ high-k materials such as metal oxide (MO) films, however high-quality MO dielectric films typically require high growth/annealing temperatures (>400° C.) and/or expensive vacuum deposition technologies to ensure acceptably low leakage currents.
Organic-inorganic hybrid materials provide both the optical, electrical, and environmental durability of inorganic materials, as well as the mechanical flexibility and properties tunability of organic materials. Organic TFTs (OTFTs) using hybrid materials combining self-assembled monolayers (SAMs) with ultra-thin MO layers such as those of HfOx, AlOx, and ZrOx that operate at low voltages have been reported. However, the SAM thicknesses of these hybrid films is limited by the singly functionalized self-assembly precursors, and multilayers self-assembled from these reported precursors typically lack well-defined growth characteristics. A key to utilizing multilayered organic-inorganic hybrid materials in unconventional TFTs and other applications is the ability to prepare high-quality multilayers in the simplest and most reliable manner. Vapor-phase fabrication methods for organic-inorganic hybrid materials are promising approaches to high-quality hybrid films; however, they typically require high- or medium-vacuum deposition equipment (e.g., atomic layer or chemical/physical vapor deposition). As such, low-cost pathways for integrating these vapor-phase fabrication methods into large-volume coating processes are not obvious. Meanwhile, although layer-by-layer solution-based deposition of well-defined organic precursors allows the realization of a range of functional materials with a high degree of order and structural control at the molecular level, the precursors often are ambient-sensitive and highly reactive, which require anhydrous atmospheres and manipulation to control their chemistry.
Therefore, there is a need in the art for organic-inorganic hybrid multilayer dielectric materials that can be prepared at low temperatures reliably from reagents suitable for ambient atmosphere fabrication, and that can afford high capacitance values as well as low leakage currents.